Membrane protein folding in the crowded environment

• Applicant: Professor Dr. Alexej A. Kedrov
• Subject Area: Biophysics ; Biochemistry ; Cell Biology
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 281307340

While being of the utmost biomedical importance, understanding of the function, structure and folding mechanisms of membrane proteins remains challenging for biomolecular sciences. Principles of protein stabilization and membrane insertion mediated by the Sec/YidC translocon have been previously investigated either in non-physiological detergent environments or in minimalistic liposome systems. However, native cellular membranes are characterized by high density of integral and peripheral membrane proteins, thus resulting in high macromolecular crowding. Macromolecular crowding affects folding and stability of soluble proteins; however, its effect on membrane protein folding has not been previously studied. Within the project I set out to investigate mechanisms of membrane protein biogenesis in native-like crowded environments. I will establish novel model membranes, which contain crowding agents, such as integral membrane proteins or membrane-associated polymers at high densities to mimic crowded conditions within cellular membranes and at their interfaces. Engineered membranes will be used to reconstitute Sec/YidC-mediated protein insertion and folding reactions. By means of biophysical and biochemical approaches the membrane protein biogenesis will be monitored from the targeting of translating ribosomes to their assembly with the Sec/YidC translocon, to the membrane protein insertion, folding and oligomerization in the crowded environment. The results will reveal potential bottleneck steps within the complex membrane protein biogenesis process and describe functional mechanisms of the translocon and membrane-associated chaperones at the challenging native-like conditions, thus building a novel framework for understanding membrane protein folding.

• DFG Programme: Research Grants